Researchers from Eindhoven University of Technology have set up a wireless network based on infrared rays. Light antennas deliver the signals at different wavelengths, allowing each device to get a 42.8Gbit/s connection.
The TU/e researchers propose a system with central light antennas that can be hung from the ceiling, for example. The signal is supplied via glass fibres, after which lenses deflect it into different wavelengths. The rays are directed to a grid which radiates them out again at different angles.
The antennas can thus direct different light frequencies to mobile devices. The researchers use wavelengths of at least 1.4 µm due to safety regulations. This prevents the infrared light from reaching the fragile retina in your eye. Adding multiple rays of light is easy, just adding wavelengths.
Mobile devices can individually receive the full bandwidth of a beam. In an experimental setup, the researchers achieved a bandwidth of 42.8 Gbit/s for a distance of 2.5 meters. This still involves one-way traffic; radio signals are still used for uploading. The returned radio signal also determines the location, so that the system knows where the infrared rays should be directed. In indoor mobile use, antennas can take over if mobile devices get out of range.
According to TU/e, the system could eventually form an alternative to Wi-Fi, with the advantage, in addition to the speed gain, being that there is no interference and network congestion. It will take at least another five years before the system is suitable for practical use, expects Professor of Broadband Technology Ton Koonen.
The positioning, among other things, still needs work, as does the central fiber optic network behind the light antennas. The research team previously published its work under the heading Ultra-high Capacity Indoor Optical Wireless Communication using Steered Pencil Beams. TU/e researcher Joanne Oh obtained her doctorate cum laude on this subject last week.